This invention relates to floor systems and more particularly to a combination wood-sheet metal floor system especially adapted for large trailers and the like.
Due to the relatively high cost of lumber, the use of metal flooring instead of wood flooring for trailers and the like has become commercially attractive. One such type of flooring comprises a plurality of elongate sheet metal floor panels extending side-by-side lengthwise of the trailer on floor supporting beams of the trailer. Each floor panel comprises an upper panel member generally in the form of an inverted channel, having a relatively wide web and stepped flanges extending down from the web at opposite sides of the web. The flange at one side of the web is stepped outwardly, having a first vertical section extending down from the web, a first horizontal section extending laterally outwardly from the lower edge of the first vertical section, a second vertical section extending down from the outer edge of the first horizontal section, and a second horizontal section extending laterally inwardly from the lower edge of the second vertical section and bearing on the trailer beams. The flange at the other side of the web is stepped inwardly, having a first vertical section extending down from the outer edge of the web member, a first horizontal section extending laterally inwardly from the lower edge of the first vertical section, a second vertical section extending down from the inner edge of the first horizontal section and a second horizontal section extending laterally inwardly from the lower edge of the second vertical section and bearing on the trailer beams. Each of the prior art floor panels also includes a series of separate inverted channel members extending longitudinally of the floor panel on the underside of the upper panel member. These channel members each comprise a web secured in face-to-face relation to the underside of the upper panel member, flanges extending down from the web at opposite sides of the web, and lips extending laterally outwardly from the lower edges of the flanges and bearing on the trailer beams.
A series of the above-described floor panels are mounted one alongside another lengthwise of the trailer with the outwardly-stepped flange at one side of a panel underlying the inwardly-stepped flange of an adjacent panel and with the inwardly-stepped flange at the other side of the panel overlying the outwardly-stepped flange of an adjacent panel. Fasteners (e.g., screws) extending down through the interfitting portions of the flanges and into the trailer beams secure the floor panels in place.
This type of flooring has presented several problems, one being that road spray, salt and other corrosive substances tend to collect on the horizontal upper faces of the lips of the inverted channel members and on the upper faces of the lower horizontal sections of the flanges at opposite sides of the upper panel members, thus increasing the rate of corrosion of the flooring. Another problem has arisen involving the securement of this type of all-metal flooring to the trailer beams. In this connection, it will be understood that fork lift trucks are often driven on the flooring as the trailer is loaded and unloaded. In the past, as wheels of the trucks have rolled over the fasteners securing the flooring to the trailer beams, the flooring around the head of the fasteners has tended to buckle or collapse, causing the flooring to become loose.